Drag constants were calibrated using a wind tunnel to gather data

The housing of the sensor is connected to a drag object by a piston.

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Force was plotted as a function of air velocity. The curve fit was weighted with error propagation and yielded the function Force=17.69*Velocity1.90

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Force = 2.141 (Velocity)1.899

Using Reynolds number conversions, a function was derived for Force as a function of Water Velocity.

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The final contour plot for Voltage as a function of time for various resistances shows that consumor batteries are far too unreliable to use for high accuracy measurement.

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The beginnings of a multivariable plot of Voltage as a function of time and resistance.

IntroductionRocky interdal shores have serve as benchmark study sites for community ecologist. The diverse ecosystems found at these sites have allowed ecologist to observe natural phenomena and processes in a matter of months, which would

otherwise take years in other environments. The severity of the physical environment, rapid turnover, frequent disturbance, and diverse community serve as base points for in depth and promising experiments.

Specifically, Mytilus californianus, the sea mussel found on rocky shores, serves as testing grounds for ecological theory. Much ecological advancement has been the outcome of experiments observing predation, recruitment, settlement and water

flow impact of this sessile benthic organism. The focus of this experiment is to observe water flow impact on mussel settlement and limitations ecologist may be faced with, due to unavailability of cost-effective and efficient instruments.

Unnecessary sophistications in sensor technology can cost researchers who are only interested in getting crude data countless dollars, creating the need for a cheaper sensor with less sophisticated technology. This research investigates the ability to tally and store average wave speeds impacting a mussel bed using spring mechanics and an electrical circuit. As water washes against objects of a known drag constant, a piston is pulled out of the sensor. As this happens, the piston extends a spring that is attached to a potentiometer which varies the electrical current in accordance with wave speed,

thereby varying the amount of time that it takes the battery’s voltage to deplete. By measuring the initial and final battery voltages, the goal was to accurately determine the average wave speed.

Methods•Two 511 Marh-McBirney Electromagnetic Water Current Meter was used for measurements of water velocity at high wave impacted exposed site and a low impacted semi-protected site.

•Two 21X Campbell Scientific Inc. data loggers were programmed to store and output minimum, maximum and average velocity readings from current meters.

•Set one 100cm2 quadrant at high impacted exposed site and one at low impact semi-protected site to measure mussel settlement.

•During low tides, the instruments would be deployment at Bird Rock. The 511 flow meter housing and 21X Campbell Scientific data logger are placed high above Bird Rock, where they are kept dry and held in place by specialized mounts.

•The design of the new flow meter was to use battery depletion to investigate the speed of the water moving past the sensor.

•A drag constant was attached to a spring which used a potentiometer to vary current through a circuit, causing the life of the battery to be a function of water velocity.

•A multivariable graph defining voltage as a function of time and resistance was created to find average wavespeed from the voltage depletion of a 9 volt battery.

•A wind tunnel was used to find force as a function of airspeed for the given drag objects. A Reynolds number conversion was used to convert air velocities to water velocities.

•From the wind tunnel data, the nessisary spring constant was found.

Conclusions• Program for 21X data logger and 511 Marsh-McBirney flow meter very efficient.

• Two sites of reference are not an accurate representation of a spatial mussel bed settlement nor does it represent the topography and total flow impact of the site, making the need for cheap accessable current meters apparent.

• Time limitation did not allow for field deployment of instruments and completion of experiment.

• New flow meter concept shows promise.

• Consumer batteries are not reliable enough for high accuracy measurements.

• Capacitor depletion seems to be a promising alteration in design.

Sam Hagen Rosa Bugarin

Acknowledgments

Kwasi ConnorDr. Robles

Dr. KhachikianDr. Guillaume

Ms. Elisa BrownREU-CSULACEA-CREST

Hartwick College California State University, LA